How to Prepare for the Test

Normally, no special preparation is needed. Tell your provider if you are taking a blood thinner, such as aspirin, warfarin (Coumadin) or clopidogrel (Plavix). These medicines can affect test results or your ability to take the test.

How the Test will Feel

Sometimes, the provider will first inject numbing medicine into the skin with a small needle, which will sting. A larger needle is then used to draw out the synovial fluid.

This test may also cause some discomfort if the tip of the needle touches bone. The procedure usually lasts less than 1 to 2 minutes. It may be longer if there is a large amount of fluid that needs to be removed.

Why the Test is Performed

The test can help diagnose the cause of pain, redness, or swelling in joints.

Osteoarthritis

Risks

Risks of this test include:

Infection of the joint -- unusual, but more common with repeated aspirations

Bleeding into the joint space

Considerations

Ice or cold packs may be applied to the joint for 24 to 36 hours after the test to reduce the swelling and joint pain. Depending on the exact problem, you can probably resume your normal activities after the procedure. Talk to your provider to determine what activity is most appropriate for you.

Joint aspiration - illustration

Synovial fluid analysis is a series of tests performed on synovial (joint) fluid to help diagnose and treat joint-related abnormalities. To obtain a synovial fluid sample, a needle is inserted into the knee between the joint space. When the needle is in place the synovial fluid is then withdrawn. The sample is sent to the lab for analysis.

Joint aspiration

illustration

Joint aspiration - illustration

Synovial fluid analysis is a series of tests performed on synovial (joint) fluid to help diagnose and treat joint-related abnormalities. To obtain a synovial fluid sample, a needle is inserted into the knee between the joint space. When the needle is in place the synovial fluid is then withdrawn. The sample is sent to the lab for analysis.